The present invention relates to displacement indicators and, more particularly, to opti-mechanical indicators by means of which very small displacements or movements of one member relative to another are visually indicated via a change in intensity or color of an indicator.
There are many situations where the indication of very small distances of displacements is needed. In the past, precision gauging instruments, such as micrometers, dial indicators, feeler gages, and electronic indicators were required to accomplish the precise setting or indicating of minute displacements in the order of 0.001 inch (25 .mu.) or less. It would obviously be preferable, especially in the field, if such instruments or gages were not needed, and if the adjustments could be visually set to within acceptable limits with the aid of a built-in indicating device, and could also be quickly inspected for a proper condition visually and without contact at a subsequent time.
One form of simplified indicator known in the prior art is a stress-strain indicator of the type described in my U.S. Pat. No. 3,602,186. Indicators of this known type employ a light absorbing indicator fluid and have provision for varying the thickness of the indicator fluid so as to vary the transmission of light therethrough. The utilization of such strain indicators more fully than at present has been hindered by such factors as cost, and complexity in design and manufacture. There is a recognized need for improved, economical microindicators.